Hydraulic shock absorber



Sept. 15, 1936. R. F. PEO

HYDRAULIC SHOCK ABSORBER Original Filed Jan. 5; 195:5

2 Sheets-Sheet l w; E E 1 z s-Sheet R. F. PEO I Original Filed Jan. 5, 1955 2 Sheet Sept. 1-5, 1936.

Patented Sept. 15, 1936 UNITED STATES PATENT OFFICE HYDRAULIC SHOCK ABSORBER Ralph F. Peo, Bufialo, N. Y., assignor to Houde Engineering Corporation, Bufialo, N. Y., a corporation of New York 5 Claims.

This invention relates to hydraulic shock absorbers, particularly to shock absorbers for association with the springs of automotive vehicles, and this application is a division of my copendgng application Serial No. 650,275, filed January In general, the object of the invention is to provide improved and simplified automatic. regulation and metering of the bypassage flow of the fluid to control the shock absorber resistance accurately and eificiently without disturbance or interference by fluid temperature or viscosity variations and without the use of thermostat mechanism. 7

In accordance with my invention I depend upon properly designed and dimensioned orifices for metering and controlling the fluid flow independently of viscosity variations, a type of orifice which will give the desirable characteristics being the so-called sharp edge orifice.

I provide a passageway through which the hydraulic fluid is forced alternately in opposite directions during operation of the piston structure in the fluid containing casing, and in'this passageway I interpose two orifices, and for one of the orifices I provide a valve, which may be in the form of a reed, for closing this orifice against flow in one direction but being yieldable for flow in the opposite direction so that for one direction of flow both orifices are available but for flow in reverse direction only one orifice is available, the valve being so arranged that the one orifice will be closed thereby by the fluid pressure during rebound movement of the vehicle springs whereby the flow during such movement will be metered by the other or permanently open orifice, both orifices being opened to the flow during the compression movement of the vehicle springs.

' On the accompanying drawings I have shown my invention applied in a well-known type of shock absorber. In the drawings Figure 1 is a diametral section of a hydraulic shock absorber taken on plane I-I of Figure 2;

Figure 2 is a section on plane 22 of Figure 1;

Figure 3 is a section on plane 3-3 of Figure 1; and

Figure 4 is an enlarged section of an efiicient type of viscosity compensating orifice.

The body of the shock absorber structure shown comprises the rear or base wall I0 having the peripheral cylindrical wall or flange II extending laterally therefrom to define a cylindrical space. Within the wall I I and abutting thereagainst and against the base I0 is the ring I2 from which extend the diamet y pp s t partition walls I3 and I4. The outer cylindrical wall or head I5 fits into the cylindrical wall I I and abuts against the ring I2 and the partition walls I3 and I4 and has the annular recess 15' at its outer end for receiving the clamping ring; I6

which has threaded engagement with the interior threads at the outer'end of the wall II, the head I5 thus being securely clamped in, position. To securely hold the ring I2 and partitions I3 and I4 in place pins or keys I! are used which extend through the partitions and into the base wall III.

The head I5 has the bearing. bore I8 which is continued through the lug or sleeve I9 extending outwardly from the head, and this bore journals the shaft 20 having at its inner end the cylindrical hub 2I which extends axially between the head I5 and the base wall Illand has the cylindrical bearing pocket 22 for receiving the centering and bearinglug 23 extending from the base Wall III. Extending radially from opposite sides of the shaft hub are the piston members 24 and 25 whose outer ends fit against the ring I2 between the partition walls I3 and I4, the piston members extending axially between the head I5 and the base wall III. The opposed ends of the partition walls are of cylindric surface to engage against the shaft hub with bearing fit, the piston members, the partition walls and the ring. I2 dividing the interior of the shock absorber intothe high pressure working chambers 26 and 26' and the low pressure chambers 2! and 2'l'.

The base wallIO has ears 28 extending therefrom by means of which the shock absorber body may be secured to a support as for example the chassis of an automotive vehicle, and the shaft at its outer end has secured thereto an arm 29 whose end is adapted for connectionas for example with the axle of the automotive vehicle so that as the vehicle travels and the vehicle body and axles move relatively, the shaft will oscillate the piston members against the resistance of a fluid such as oil in the working chambers.

The high pressure chambers 26 and 26' are always in communication with each other through a duct 30 extending diametrally through the hub 2I and the low pressure chambers 21 and 21 are always in communication through a duct 3I through the hub, the ends of these ducts being close to the bases of the piston or vane members 24 and 25.

As shown, one of the piston or vane members is provided with a fluid bypassageway 32 extending transversely therethrough, this bypassageway having the enlarged end 33 opening to shown is held in the pocket 34 by the annular.

flange 31 extending therefrom, a cup-shaped structure being thus provided through whose bottom extends the orifice 36. a

The wall 35 through which the oriflceextends is comparatively thin but is rigid and inflexible and the orifice shown is of the so-called standard sharp edge type shown more in detail in Figure 4 with its sharp edge 38 in the plane of the outer face of the wall 35 so that the coeflicient of discharge of the fluid from the high pressure chambers to the low pressure chambers will be substantially independent of the viscosity of the fluid. In other words with this particular type of orifice or other shape orifice having the same characteristics as the type shown, the reaction .or resistance to flow through the orifice measured in the pressure of the fluid under a definite displacement per unit of time will, for all practical purposes, remain unchanged during variation .of the viscosity of the fluid.

V The flow resistance through the orifice will increase with'increase of the head or pressure which tends to. force the fluidthrough the orifice. Such functioning .of theorifice is'very desirable in the operation of the shock absorber as increased opposition to fluid flow will be built up in proportion to the increasing rebound energy tending to rapidly move the piston for expulsion of the fluid through the orifice, and the shock absorber resistance will be more proportionate to the severity of road conditions.

During the high compression stroke of the piston structure occurring during rebound or move-- ment of the chassis away ,from the axle, the resistance .and shock absorption is controlled en- ,tirely by the flow through the restricted orifice 3.6. During the low compression stroke of the piston occurring when the chassis and axle approach each otherthe bypass restriction is considerably less. A larger orifice or port 39 communicates with the bypassageway 32 and as shown this port may be located in the wall '35 at one s de of the orifice 36. A suitable valve is provided to check flow through this port during the pressure stroke .of the piston structure. I have shown a med valve 40 secured as by a screw 4| against the face of the piston vane adjacent to. the bypass pocket 34 with its free end of reduced width to extend over the outer endof the port 39 During the pressure stroke this port will be closed by the valve reed and the only flow must be through the metering orifice 36. During the low compression stroke of the piston. structure the fluid pressure will raise the valve so that flow may both through the orifice and the port. The section 32 of the bypassageway is comparatively large and will ofier very little resistance 'tothe low' pressure flow of fluid. The port 3'9 being of larger diameter than the orifice 36 will offer much less obstruction and in order that the low compression flow resistance through the port 39 may compensate for variation in viscosity of the fluid the port may be beveledi away at its outer side so as to chambers.

present, in offset, a sharp edge orifice to the low compression flow.

As shown on Figure 1 a casing or cap 66 is applied to the frame H to provide a replenishing chamber 61. Communicating with the lower ends of each of the chambers 26 and 21 in a replenishing passageway 68 controlled 'by a ball valve 69, the valve closing the passageway during compression of the fluid in the'respective The upper end of each of the chambers 26' and 21 communicates with a restricted passageway 10 which, as shown, is in the form of a slot cut in a plug H extending through the head .15. .At each plug a well structure 12 is provided whose walls form part of the head' 15,

the upper ends of the wells being shown above the-passageway l0 and the bottoms of the wells communicating with an annular channel 13 formed in the bearing l9. Any fluid which may leak out between the piston hub and its shaft and the bearing ill will be collected by the channel and will rise in the wells and keep the respective relief channels 10 covered and sealed against the return of air to the working chambers at the top thereof.

I have shown a practical and efflcien-t em. bodiment of the various features of my invention but I do not desire to be limited to the exact construction and arrangement shown and described as changes and modifications may be made without departing from the scope oi the invention as defined in the appended claims.

I claim as my invention: 7 a i 1. In a hydraulic shock absorber, a housing-em closing a high pressure chamber and a low pressure chamber, a piston operable to displace fluid in said chambers a passage between said chambers for flow of the displaced fluid, means providing an orifice permanently open for a restricted but unobstructed flow of liquid between said.

chambers at a rate substantially independent of viscosity changes in the liquid and a second orifice in said passage for additional flow therethrough, and means controlled by the pressure of the fluid for closing said second orifice against flow from the high pressure chamber to the low pressure chamber.

2. In a hydraulic shock absorber, a housing enclosing a high pressure chamber and a low pressure chamber, a piston operable to displace fluid in said chambers, a passage between said chambers for the flow of the displaced fluid, means providing two orifices for said passage for a restricted flow of fluid between said chambers at a rate substantially independent of viscosity, changes in the fluid, one of said orifices being permanently open for unobstructed flow therethrough and means controlled by the pressure of the fluid for closing the other orifice against flow from the high pressure chamber to the low pressure chamber.

3. In a hydraulic shock absorber, a fluid chamber, a member movable in said chamber to displace fluiid therein, a by-pass for flow of fluid from one side of said member to the other during movement of said member, a rigid disc interposed in said by-pass and having an orifice and a port therethrough, said orifice being permanently open for unobstructed flow therethrough and being of the sharp edged type thru which the rate of flow is practically independent of viscosity changes in the liquid flowing therethrough, a check valve movable by the pressure of the fluid to close said port whereby all the fluid flow in one direction through said by-pass must be through said orifice,

said check valve yielding to the pressure in the opposite direction for flow of the fluid through both said port and said orifice.

4. In a hydraulic shock absorber, a chamber for confining fluid, a member movable in said chamber to displace the fluid therein, a by-pass for flow of fluid from one side of the movable member to the other, a wall interposed in said by-pass having two orifices therethrough one of which is restricted more than the other but being permanently open for unobstructed flow therethrough, a valve for closing the less restricted orifice against flow when said member moves in one direction and for opening said orifice when the member moves in the opposite direction, each of said. orifices being of a type through which the rate of flow is substantially independent of viscosity changes in the liquid flowing therethrough.

5. In a hydraulic shock absorber, a housing enclosing a high pressure chamber and a low pressure chamber, a piston operable to displace fluid in said chambers, a passage between said chambers for flow of the displaced fluid, a restricted orifice in said passage for flow of fluid between said chambers at a rate substantially independent of viscosity changes in the fluid, and a second orifice in said passage for additional flow therethrough, and a member having a flap portion cooperating with said second orifice and controlled by the pressure of the fluid for closing said second orifice against flow from the high pressure to the low pressure chamber.

RALPH F. PEO. 

